JP6398671B2 - Method for firing ceramic molded body and method for manufacturing pressure sensor - Google Patents

Description

  The present invention relates to a method for firing a ceramic molded body and a method for manufacturing a pressure sensor to which the firing method is applied.

  Conventionally, a method of joining two ceramic molded bodies is known. For example, in the joining method of the SiC sintered body disclosed in Patent Document 1, the joining interface is obtained by bringing the center parts of two SiC sintered bodies having a joining surface convex toward the center part into contact with each other. It is difficult for voids to be formed.

Japanese Patent Laid-Open No. 2014-9114

Suppressing the gap at the bonding interface by the technique of Patent Document 1 leads to the prevention of “void” in which air remaining at the interface is trapped. In general, the presence of voids in a product leads to a decrease in bonding strength.
Further, for example, in a back pressure-receiving pressure sensor that detects fluid pressure, a metal housing having a thin portion that is distorted by pressure is a first adherend, and a sensor chip that outputs a pressure signal to the outside is a second adherend. When the glass layer that transmits the distortion of the part to the sensor chip is a ceramic molded body, if a void occurs between the glass layer and the sensor chip, the detection accuracy decreases due to the difference in conductivity between the glass and air There is.
Thus, in the firing of the ceramic molded body, the realization of the boyless is required.

By the way, in the joining method in which convex shaped bodies as disclosed in Patent Document 1 are brought into contact with each other, the joining load becomes non-uniform depending on the position, and there may be a problem in quality depending on the application of the applied product.
In addition, when mass-producing convex shaped bodies, it is difficult to manufacture the height and curvature of the curved surface with high accuracy and constant, resulting in variations. For this reason, the contact position and bonding load when the molded bodies are bonded to each other may vary, and the quality may not be stable.

  The present invention has been made in view of the above-described problems, and its purpose is to prevent generation of voids while ensuring a stable bonding state when firing a ceramic molded body sandwiched between two layers of adherends. An object of the present invention is to provide a method for firing a ceramic molded body that is suitably suppressed.

  In the present invention, between the first adherend of the lower layer and the second adherend of the upper layer, “the same position or inside with respect to the outline of the first adherend and the same with respect to the outline of the second adherend. A firing method for firing a ceramic molded body sandwiching a “ceramic molded body whose outline is located at a position or outside”, and includes an assembly process and a firing process.

The present invention provides the following four methods with different aspects of the assembly process and the firing process. All of these four methods suppress the generation of voids by efficiently discharging the air between the ceramic molded body and the second adherend. Moreover, compared with the prior art, there is a common effect in that the variation in bonding can be reduced and a stable bonding state can be secured. The “first invention” is a reference form.

(Method for firing ceramic molded body of the first invention)
In the assembling step, a second adherend having a through hole at the center is further placed on the ceramic molded body placed on the first adherend. In the firing step, the ceramic molded body is fired while discharging air from the through holes.

(Method for firing ceramic molded body of the second invention)
In the assembling process, a contact surface end which is one end of the second adherend is brought into contact with the ceramic compact on the ceramic compact placed on the first adherend, and the other of the second adherend is contacted. Is placed so as to be spaced apart from the ceramic molded body. In the firing step, while discharging air from the contact surface end of the second adherend toward the separation surface end, the fired ceramic molded body and the second adherend are moved from the contact surface end toward the separation surface end. Join sequentially.

(Method for firing ceramic molded body of the third invention)
In the assembly process, the second adherend is further placed on the ceramic molded body placed on the first adherend. In the firing step, by locally heating the central portion of the ceramic molded body, the ceramic molded body is moved from the central portion toward the periphery while discharging air from the central portion of the second adherend toward the peripheral portion. Bake.

(Method for firing ceramic molded body of the fourth invention)
In the assembly process, the second adherend is further placed on the ceramic molded body placed on the first adherend. In the firing step, the ceramic molded body is fired from one side to the other side while discharging air from one side of the second adherend to the other side.

The firing method of the ceramic molded body can be effectively applied to, for example, a pressure sensor manufacturing method. This pressure sensor is a back pressure receiving type that detects the fluid pressure by transmitting the strain generated by the fluid pressure acting on the thin wall portion formed inside the pressure introduction hole of the metal housing to the sensor chip through the glass layer. In the pressure sensor, the metal housing, the glass layer, and the sensor chip correspond to the first adherend, the ceramic compact, and the second adherend, respectively, in the firing method of the ceramic compact.
In this pressure sensor manufacturing method, the generation of voids between the glass layer and the sensor chip is suppressed to prevent a decrease in bonding strength, and the detection accuracy of the sensor is achieved by making the conductivity of the glass layer uniform. Can be improved.

The schematic diagram of the pressure sensor to which the baking method of the ceramic molded object of embodiment of this invention is applied. The schematic diagram which shows the assembly | attachment process by the baking method of the ceramic molded body of 1st Embodiment of this invention. The schematic diagram which shows the baking process by the baking method of a ceramic molded body same as the above. The schematic diagram which shows the assembly process by the baking method of the ceramic molded body by 2nd Embodiment of this invention. The schematic diagram which shows the baking process by the baking method of a ceramic molded body same as the above. The schematic diagram which shows the baking process by the baking method of a ceramic molded body same as the above. The schematic diagram which shows the assembly process by the baking method of the ceramic molded body by 3rd Embodiment of this invention. The schematic diagram which shows the baking process of the baking method of a ceramic molded body same as the above. The schematic diagram which shows the assembly process by the baking method of the ceramic molded body by 3rd Embodiment of this invention. The schematic diagram which shows the baking process by the baking method of a ceramic molded body same as the above.

Hereinafter, a method for firing a ceramic molded body according to a plurality of embodiments of the present invention and a method for manufacturing a pressure sensor to which this firing method is applied will be described with reference to the drawings.
First, a schematic configuration of the pressure sensor 9 which is a product of the “pressure sensor manufacturing method” will be described with reference to FIG. The pressure sensor 9 shown in FIG. 1 is assumed to be manufactured by the conventional “ceramic molded body firing method”. The pressure sensor 9 is a “backside pressure receiving type” pressure sensor that detects a fluid pressure of fuel or the like, and has the same function as the pressure sensor disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-145316.

  The pressure sensor 9 mainly includes a metal housing 1, a glass layer 3, and a sensor chip 4. In addition, illustration and description of a low part relevant to basic functions, such as a screw part of the metal housing 1, are omitted. Further, the meaning of hatching or the like of each member conforms to the notes in FIGS.

  In the metal housing 1, a pressure introducing hole 12 is formed along the central axis of the cylindrical portion 11, and the bottom of the pressure introducing hole 12 is a thin portion 13. As indicated by the arrow Pf, the fluid pressure of the fuel or the like introduced into the pressure introduction hole 12 acts on the thin portion 13 to cause distortion. The glass layer 3 transmits strain generated in the thin portion 13 to the sensor chip 4. The sensor chip 4 is a silicon chip, for example, and outputs the transmitted pressure signal to an external detection device via the signal line So.

In the manufacturing process of the pressure sensor 9, the glass layer 3 is baked and bonded to the silicon chip 4. In this firing step, if the air between the glass layer 3 and the silicon chip 4 is not properly discharged, the air is confined and joined, and a void V as shown in FIG. 1A is generated.
In general, when a void V is generated at a joint portion between members, the joint strength is reduced. In particular, the pressure sensor 9 has a problem that the transmission of strain becomes inaccurate due to the difference in conductivity between glass and air, which causes a decrease in detection accuracy.

Conventionally, as a method for suppressing the generation of voids V, a method of joining convex shaped bodies together as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2014-9114) has been disclosed. However, in the joining method in which the convex shaped bodies are brought into contact with each other, the joining load becomes uneven depending on the position. In addition, when mass-producing convex shaped bodies, it is difficult to produce a curved surface with a high height and curvature with high accuracy, resulting in variations in the joining state.
Then, it aims at suppressing the generation | occurrence | production of a void suitably, ensuring the stable joining state in the baking method of the ceramic molded body by embodiment of this invention.

Hereinafter, the firing method of the ceramic molded body of the first to fourth embodiments will be described in order with reference to FIGS. These embodiments are suitably applied as a manufacturing method of the pressure sensor 9, for example, but are not limited to this, and can be established as a general-purpose firing method.
Therefore, the names of “metal housing”, “glass layer” and “sensor chip” in the pressure sensor 9 are changed to “first adherend”, “ceramic molded body” and “second adherend”, respectively. It will be described in a generalized form. Further, in the illustration of the first adherend 1, the illustration of the cylindrical portion 11, the pressure introducing hole 12, and the like that are unique to the metal housing of the pressure sensor 9 is omitted.

The firing method of the ceramic molded body of each embodiment is generally a method in which the ceramic molded body 2 is sandwiched as an intermediate layer between the lower first adherend 1 and the upper second adherend 4 and fired. is there.
For example, the first adherend 1 is a metal such as stainless steel or ceramic, the ceramic molded body 2 is glass, and the second adherend 4 is a metal such as silicon or ceramic.

  Here, the ceramic molded body is distinguished as “2” before firing and “3” after firing. Moreover, about the 2nd to-be-adhered body of 1st Embodiment, since it has a through-hole which is not in other embodiment, exclusive code | symbol "43" is attached | subjected. However, in the common description, the “second adherend 4” includes the second adherend 43 of the first embodiment. The first adherend 1 and the ceramic molded body 2 have substantially the same specifications in any of the embodiments. In the plurality of embodiments, substantially the same configuration is denoted by the same reference numeral, and description thereof is omitted.

Next, the relationship between the sizes of the first adherend 1, the ceramic compact 2, and the second adherend 4, particularly the contour position when viewed from above, will be described.
The contour of the ceramic molded body 2 is located at the same position or inside of the first adherend 1. In each figure, although the case where the outline of the ceramic molded body 2 and the 1st to-be-adhered body 1 is the same position is illustrated, the ceramic molded body 2 may be smaller than the 1st to-be-adhered body 1. FIG.

Further, the contour of the ceramic molded body 2 is located at the same position or outside of the second adherend 4. In each figure, the case where the square second adherend 4 is clearly smaller than the circular ceramic molded body 2 is illustrated. However, the contour of the second adherend 4 is slightly smaller than the contour of the ceramic molded body 2. May be located inside or at the same position. The shape of each member 1, 2, 4 may be any of a circle, a rectangle, another polygon, and the like.
In short, if the contour of the upper layer in the direction of gravity protrudes outside the contour of the lower layer, there is a risk of dripping when heated. Therefore, it is a precondition for carrying out this firing method that the contour of the lower layer is located at the same position or outside of the contour of the upper layer.

Next, common precautions in the illustrations of FIGS. 2 to 10 will be described.
About the 1st to-be-adhered body 1, in (b) sectional drawing, a cross section is represented by the solid line hatching with a rough pitch.
Regarding the ceramic molded bodies 2 and 3, the ceramic molded body 2 before firing is indicated by broken line hatching, and the ceramic molded body 3 after firing is indicated by solid line hatching with a fine pitch. These hatchings are described not only in (b) sectional view but also in (a) plan view for the purpose of distinguishing before and after firing.

The fired ceramic molded body 3 is bonded to the second adherend 4 to form a bonded portion 35. This joint portion 35 is represented by cross hatching in FIG. This cross hatching expresses the progress of joining and does not mean a cross section.
In the (a) plan view, the second adherend 4 represents only the outline except for the joint portion 35, and in the (b) cross-sectional view, the cross-section is represented by medium pitch hatching.
As described above, in the drawings of the present specification, the distinction between the real view and the cross-sectional view is obvious, and the importance of specifying the material depending on the type of hatching is low. Rather, hatching is used to express state changes accompanying the progress of the process in an easy-to-understand manner.

A method of firing the ceramic molded body according to the first embodiment as a reference form will be described with reference to FIGS. This firing method is suitable for a batch processing step using a furnace, and the ceramic molded body 2 is molded at a temperature of, for example, 400 ° C. or higher.
In the assembly process shown in FIG. 2, a second adherend 43 having a through hole 45 at the center is further placed on the ceramic molded body 2 placed on the first adherend 1. As described above, the first embodiment is characterized by using the second adherend 43 having the through hole 45 in the center.
Here, the through hole 45 in the central portion is not limited to the exact center, and may be formed near the center. The shape of the through hole is not limited to a circle, and a plurality of small through holes may be formed.

  In the firing step shown in FIG. 3, the ceramic molded body 2 of FIG. 2 is fired. The fired ceramic molded body 3 tends to warp so that the peripheral edge is separated from the first adherend 1. Therefore, in the second adherend 43, the four peripheral ends 44 come into contact with the ceramic molded body 3, and the center part is in a state of floating from the surface of the ceramic molded body 3. Therefore, the joint 35 between the second adherend 43 and the ceramic molded body 3 spreads inward from the peripheral end 44 in order. At this time, the air A accumulated in the space between the second adherend 43 and the ceramic molded body 3 is efficiently discharged to the outside through the through hole 45 in the central portion as indicated by an arrow.

Thereby, generation | occurrence | production of the void in the baking process of a ceramic molded body can be suppressed, and quality can be improved. In addition, when this ceramic molded body firing step is applied to the manufacturing method of the pressure sensor 9, it is possible to make the pressure conductivity uniform and improve the detection accuracy by not introducing voids into the glass layer that is the ceramic molded body. it can.
Furthermore, unlike the prior art of Patent Document 1, it is not necessary to form the molded body into a convex shape, so that the bonding load depending on the position becomes uniform. In addition, there are few factors that cause individual variations in the shape of the molded body. Therefore, it is possible to reduce the variation in bonding in mass production and ensure a stable bonding state.

  By the way, with respect to the discharge path of the air A, the air A between the ceramic molded body 3 with the peripheral edge warped and the lower first adherend 1 is discharged from the central part toward the peripheral part as shown in FIG. Is done. The discharge of air A between the ceramic molded body 3 and the first adherend 1 is the same in the following embodiments. In the following embodiments, in order to emphasize main features, illustration of warping of the ceramic molded body 3 and discharge of air A between the ceramic molded body 3 and the first adherend 1 is omitted.

(Second Embodiment)
A method for firing a ceramic molded body according to a second embodiment of the present invention will be described with reference to FIGS. In the firing method of the second embodiment, the second adherend 4 held while being tilted with respect to the fired ceramic molded body 3 is fired from one end to the other end while firing the ceramic molded body 2. It is characterized in that the ceramic molded body 2 is contacted and joined in order. This firing method is suitable for batch processing using a furnace, as in the first embodiment.

  In the assembling process shown in FIG. 4, the “contact surface end 41” that is one end portion of the second adherend 4 is formed on the ceramic formed body 2 placed on the first adherend 1. The “separation end 42” which is the other end of the second adherend 4 is inclined and placed so as to be separated from the ceramic molded body 2. For example, the inclined state can be realized by interposing the spacer 5 between the separation end 42 of the second adherend 4 and the ceramic molded body 2. In FIG. 4, a cylindrical rod-shaped member is used as the spacer 5, but the shape of the spacer 5 is not limited to this. Further, instead of the spacer 5, the separation end 42 of the second adherend 4 may be pulled up from above.

5 and 6 show a series of firing steps divided over time. In the first half stage shown in FIG. 5, a portion near the contact surface end 41 of the second adherend 4 is brought into contact with the fired ceramic molded body 3 to form a joint portion 35. As indicated by the arrows, the air A is discharged from the contact surface end 41 side toward the open space on the separation surface end 42 side.
In this way, the joint portion 35 spreads from the contact surface end 41 side toward the separation surface end 42 side. As shown in FIG. 6, the spacer 5 is moved in the direction of the arrow M and removed at the latter half stage where the joining portion 35 is formed on most of the second adherend 4.

In this way, the fired ceramic molded body 3 and the second adherend 4 are sequentially joined from the contact surface end 41 toward the separation surface end 42 with the transfer of heat from the contact surface end 41. Accordingly, the air A between the ceramic molded body 2 and the second adherend 4 is discharged from the contact surface end 41 toward the separation surface end 42.
Therefore, this firing method also has the same effect as the firing method of the first embodiment.

(Third embodiment)
A method for firing a ceramic molded body according to a third embodiment of the present invention will be described with reference to FIGS. The firing method of the third embodiment is characterized in that a laser heating device 6 is used as a local heating means and the central portion of the ceramic molded body 2 is locally heated. This firing method is suitable for a single-flow process.

In FIGS. 7 and 8, the pressure introducing hole 12 and the thin portion 13 of the first adherend 1, which are not illustrated in other embodiments, are intentionally shown in order to represent the characteristics of laser heating. That is, when the metal housing of the pressure sensor 9 is used as the first adherend 1, the laser heating device 6 is provided on the extension line of the pressure introduction hole 12, thereby aiming the irradiation direction of the laser light L in the pressure introduction hole 12. It is determined in the central axis direction, and the central portion of the ceramic molded body 2 can be efficiently locally heated through the thin portion 13.
However, even when a member having no hole or thin portion at the center is used as the first adherend 1, local heating with the laser beam L is possible.

In the assembly process shown in FIG. 7, the second adherend 4 is further placed on the ceramic molded body 2 placed on the first adherend 1. There are no special features at this stage.
In the firing step shown in FIG. 8, the laser beam L is emitted from the laser heating device 6 installed below the first adherend 1 toward the center of the ceramic molded body 2 located in the back of the pressure introduction hole 12. Irradiate. Thereby, the center part of the ceramic molded body 2 is heated locally. As the heat is transmitted from the central portion, the joint portion 35 between the ceramic molded body 2 and the second adherend 4 spreads from the central portion toward the peripheral portion. Accordingly, air A between the ceramic molded body 2 and the second adherend 4 is discharged radially from the central portion toward the peripheral portion.
Therefore, this firing method also has the same effect as the firing method of the first embodiment.

(Fourth embodiment)
A method for firing a ceramic molded body according to a fourth embodiment of the present invention will be described with reference to FIGS. The firing method of the fourth embodiment is characterized in that an infrared (IR) heater 7 is used as a radiant heating means and the ceramic molded body 2 is heated from one side. This firing method is suitable for a step of firing a plurality of ceramic molded bodies 2 arranged in a row at a time.

  9 and 10, “70” indicates the main body of the infrared heater device, and “7” indicates the infrared heater. The infrared heater 7 is disposed at the left end of the ceramic molded bodies 2 and 3 in each of the drawings (a) and (b) so as to extend in the vertical direction in each of the drawings (a) and in the front-to-back direction in the drawing. Has been. A set of assembly parts including the first adherend 1, the ceramic compact 2, and the second adherend 4 may be arranged in a row along the infrared heater 7.

In the assembly process shown in FIG. 9, the second adherend 4 is further placed on the ceramic molded body 2 placed on the first adherend 1. There are no special features at this stage.
In the firing step shown in FIG. 10, the ceramic molded body 2 is fired from one side (left side in the figure) to the other side (right side in the figure) by the radiant heat of the infrared heater 7. The interface between the fired ceramic molded body 3 and the second adherend 4 forms a joint 35. Accordingly, the air A between the ceramic molded body 2 and the second adherend 4 is discharged from the infrared heater 7 side (one side) toward the opposite side (the other side).
Therefore, this firing method also has the same effect as the firing method of the first embodiment.

(Other embodiments)
(A) As described above, the first adherend 1, the ceramic molded body 2, and the second adherend 4 may have any shape as long as the conditions of the contour position relationship are satisfied.
(A) Regarding the material, the glass layer used as the ceramic molded body 2 may be lead glass, silica alumina glass, or the like. As the first adherend 1 and the second adherend 4, metal, ceramic, or the like can be applied. For example, a suitable one is selected depending on the combination with the ceramic molded body 2.

(C) The method for firing a ceramic molded body according to the present invention can be used for manufacturing, testing, refurbishing and the like of various products in addition to a pressure sensor.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

1 ... first adherend, metal housing,
2 ... Ceramic molded body (before firing),
3 ... Ceramic molded body (after firing), glass layer,
4, 43 ... second adherend, sensor chip, 41 ... contact end, 42 ... separation end,
45 ... through-hole,
9: Pressure sensor.

Claims (4)

Between the lower first adherend (1) and the upper second adherend (4), at the same position or inside the outline of the first adherend and the outline of the second adherend Is a firing method of sandwiching the ceramic molded body (2) whose contour is located at the same position or outside, and firing the ceramic molded body,
On the ceramic molded body placed on the first adherend, a contact surface end (41) which is one end of the second adherend is brought into contact with the ceramic molded body, and the second adherend is placed. An assembling process in which the separated end (42) which is the other end of the adherend is placed so as to be separated from the ceramic molded body;
While discharging air from the contact surface end of the second adherend toward the separation surface end, the fired ceramic molded body and the second adherend are moved from the contact surface end to the separation surface end. Firing step of sequentially joining toward the
A method for firing a ceramic molded body comprising: Between the lower first adherend (1) and the upper second adherend (4), at the same position or inside the outline of the first adherend and the outline of the second adherend Is a firing method of sandwiching the ceramic molded body (2) whose contour is located at the same position or outside, and firing the ceramic molded body,
An assembling step of further placing the second adherend on the ceramic molded body placed on the first adherend;
By locally heating the central part of the ceramic molded body, the ceramic molded body is fired from the central part to the periphery while discharging air from the central part of the second adherend to the peripheral part. A firing step,
A method for firing a ceramic molded body comprising: Between the lower first adherend (1) and the upper second adherend (4), at the same position or inside the outline of the first adherend and the outline of the second adherend Is a firing method of sandwiching the ceramic molded body (2) whose contour is located at the same position or outside, and firing the ceramic molded body,
An assembling step of further placing the second adherend on the ceramic molded body placed on the first adherend;
A firing step of firing the ceramic molded body from the one side toward the other side while discharging air from one side of the second adherend toward the other side;
A method for firing a ceramic molded body comprising: The strain generated by the fluid pressure acting on the thin wall portion (13) formed inside the pressure introduction hole (12) of the metal housing (1) is transmitted to the sensor chip (4) through the glass layer (3). , A manufacturing method of a back pressure receiving type pressure sensor (9) for detecting fluid pressure,
In the firing method of the ceramic molded body according to any one of claims 1 to 3 ,
The method of manufacturing a pressure sensor, wherein the metal housing, the glass layer, and the sensor chip correspond to the first adherend, the ceramic molded body, and the second adherend, respectively.

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